Field of the Invention
This invention relates to a method for direct synthesis of nitrogen-containing polymers, and particularly to the production of nitrogen-containing polymeric materials in a single step Friedel-Crafts polymerization of olefinic materials containing substantial amounts of isobutylene. Nitrogen-containing functional groups such as the azide, cyano, carbonylamino or thiocarbonylamino groups are advantageous since it is a polar group which imparts good properties to a polyolefinic substrate. Also, these groups may act as a reactive site for further modification of the polymer. Nitrogen-containing polyisobutylenes have applications such as lube additives, compatibilizers, emulsifiers, and the like. For example, azide terminal polymers may be further modified by, for instance, phthalamidation or reduction of the azide group and thus result in polymer products with useful modifications. For instance, reduction of the azide group of polyisobutylenes and addition of a polar moiety to the alpha nitrogen atom may result in improved polymeric compatibilizers, emulsifiers, etc.
Prior art processes for synthesis of polymers having nitrogen-containing functional groups, such as nitrogen-containing polyisobutylene, involved several reaction steps. Chain end functionalization is known in the field of cationic polymerization. Chain end functionalization may result from transfer reactions such as those described in U.S. Pat. No. 4,568,732 which relates to a continuous process for forming telechelic halogenated polymers wherein a cationically polymerizable monomer and an inifer (initiator-transfer agent) are contacted with a boron chloride solvent solution. Disclosed monomers are olefins of from 4 to 12 carbon atoms, e.g., isobutylene. Suitable inifers are halogenated aromatic or aliphatic hydrocarbons, vinyl halides, silane-substituted hydrocarbyl halides, dicyclopentadienyl halides, alpha-chlorostyrene homopolymers, and 2-chloro-propene homopolymers and copolymers, wherein the halide is F, Cl or Br. U.S. Pat. No. 4,611,037 relates to a process for preparing polymers having reactive halogen end groups employing cationically polymerizable monomers and a catalyst system consisting of a metal halide and an organic halide, wherein the metal halide is used in from 2 to 500 times molar excess, based on the organic halide.
Chain end functionalization may also be accomplished by termination reactions wherein a functional group is imparted to the electrophilic site of a developing polymer. Such systems entail high manufacturing costs and expend considerable process control resources due to the number of reaction steps involved.
U.S. Pat. No. 3,684,713 relates to lubricating oil and fuel compositions containing oil-soluble azo compounds prepared by reacting an oil-soluble, synthetic organic polymer having at least 20 carbon atoms with an azo compound (e.g., azo esters, azo amides such as azodiformates and azodiformamides) at temperatures of from 20.degree. to 200.degree. C. Oil-soluble polymers are disclosed to include polybutenes, and copolymers of isobutylene/styrene and isobutylene/1-decene.
U.S. Pat. No. 4,393,199 discloses a cationic polymerization method to produce low molecular weight polymers wherein cyclic ethers (e.g., bis(azidomethyl)oxetane-3) are polymerized in the presence of a diol/cationic catalyst for molecular weight control.
U.S. Pat. No. 4,483,978 relates to energetic copolymers by copolymerization of azido monomers (e.g., bis(azidomethyl)oxetane), wherein the N.sub.3 azido group is bonded directly to a ring carbon atom, with a cyclic oxide.
U.S. Pat. Nos. 3,993,609 and 4,029,615 relate to polymeric cellular structures obtained by mixing an acid sensitive azo compound with an acidulous or acidic polymerizable medium, such as unsaturated polyesters and polymeric active resins containing one or more terminal and/or pendant functional groups that undergo free radical reaction.
U.S. Pat. Nos. 3,645,917; 4,268,450; and 4,405,762 relate to polymers having pendant alkylazide sidegroups prepared by reaction of a polymer with a metal azide. In U.S. Pat. No. 3,645,917, a polyether polymer is prepared from epichlorohydrin, and then reacted with a metal azide (e.g., sodium azide) at 30.degree. C. to 150.degree. C. to form azidomethyl groups pendant from the main polyether polymer backbone. Polyether and polyester polymers are disclosed in U.S. Pat. No. 4,268,450 to be reacted with sodium azide at 100.degree. C. to form energetic hydroxy-terminated azido polymers having pendant alkyl azide groups. In U.S. Pat. No. 4,405,762, 3,3-bischloromethyloxyetane is polymerized to yield halomethyl polymer products having hydroxy functionality which are then reacted with metal azide to form poly(azido methyl oxetanes), which are disclosed to be useful as energenic binders for (e.g.) explosives.
U.S. Pat. No. 4,113,804 discloses compositions comprising polybutene EPDM and polyolefin which are cross-linked by use of chemical free-radical generators or cross-linking agents which are disclosed to include azido formates (e.g., tetramethylenebis(azido formate)), aromatic polyamides (e.g., 4,4'-diphenylmethane diazide) and sulfonazides (e.g., p,p'-oxybis-(benzene sulfonyl azide).
European Patent Application 206,756 relates to olefin polymers such as polyisobutylene, polystyrene, polyoctene and polypropylene which are polymerized in the presence of a preformed catalyst complex of an organic acid or its ester and a Lewis acid, preferably boron trichloride. It is disclosed that the polymerization is believed to occur, e.g. in use of a catalyst complex of an ester and boron trichloride, by the opening of the ester bond and monomer insertion. The organic acids are disclosed to be mono-, di- and tri-carboxylic acids and acids containing chloride, formate, allylic, acrylic or methacrylic.